Fully implanted battery-free high power platform for chronic spinal and muscular functional electrical stimulation

Area of Science:

• Biomedical Engineering
• Neuroscience
• Electrical Engineering

Background:

• Chronic electrical stimulation of the neuromuscular system has significant therapeutic potential.
• Existing wireless power transfer systems lack the necessary power and voltage for demanding applications like muscle stimulation.
• Battery packs and external connections pose challenges for long-term implanted devices.

Purpose of the Study:

• To develop an optimized passive resonator for efficient wireless power transfer.
• To overcome limitations of current systems in delivering high power and voltage for neuromuscular stimulation.
• To demonstrate the feasibility of chronic, controlled electrical stimulation in freely behaving animals.

Main Methods:

• Designed and implemented a passive resonator optimized for near field power transfer.
• Achieved high voltage (± 20 V) and power (300 mW) at a small device volume (0.2 cm²).
• Enabled multichannel, biphasic, current-controlled stimulation with digital control and telemetry.

Main Results:

• Demonstrated a 500% improvement in power transfer efficiency over previous systems.
• Successfully performed chronic implantation and operation of the device in rats for over 6 weeks.
• Showcased fine control of spinal and muscle stimulation in both intact and spinal cord injured animals.

Conclusions:

• The optimized wireless power transfer system significantly advances the capabilities for chronic neuromuscular stimulation.
• This technology enables new possibilities for scientific research and therapeutic interventions.
• The system's reliability and performance in animal models suggest its potential for clinical translation.